text: /*
   *	Anycast support for IPv6
   *	Linux INET6 implementation
   *
   *	Authors:
   *	David L Stevens (dlstevens@us.ibm.com)
   *
   *	based heavily on net/ipv6/mcast.c
   *
   *	This program is free software; you can redistribute it and/or
   *      modify it under the terms of the GNU General Public License
   *      as published by the Free Software Foundation; either version
   *      2 of the License, or (at your option) any later version.
   */
  
  #include <linux/capability.h>
  #include <linux/module.h>
  #include <linux/errno.h>
  #include <linux/types.h>
  #include <linux/random.h>
  #include <linux/string.h>
  #include <linux/socket.h>
  #include <linux/sockios.h>
  #include <linux/net.h>
  #include <linux/in6.h>
  #include <linux/netdevice.h>
  #include <linux/if_arp.h>
  #include <linux/route.h>
  #include <linux/init.h>
  #include <linux/proc_fs.h>
  #include <linux/seq_file.h>
  #include <linux/slab.h>
  
  #include <net/net_namespace.h>
  #include <net/sock.h>
  #include <net/snmp.h>
  
  #include <net/ipv6.h>
  #include <net/protocol.h>
  #include <net/if_inet6.h>
  #include <net/ndisc.h>
  #include <net/addrconf.h>
  #include <net/ip6_route.h>
  
  #include <net/checksum.h>
  
  static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr);
  
  /* Big ac list lock for all the sockets */
  static DEFINE_RWLOCK(ipv6_sk_ac_lock);
  
  
  /*
   *	socket join an anycast group
   */
  
  int ipv6_sock_ac_join(struct sock *sk, int ifindex, const struct in6_addr *addr)
  {
  	struct ipv6_pinfo *np = inet6_sk(sk);
  	struct net_device *dev = NULL;
  	struct inet6_dev *idev;
  	struct ipv6_ac_socklist *pac;
  	struct net *net = sock_net(sk);
  	int	ishost = !net->ipv6.devconf_all->forwarding;
  	int	err = 0;
  
  	if (!capable(CAP_NET_ADMIN))
  		return -EPERM;
  	if (ipv6_addr_is_multicast(addr))
  		return -EINVAL;
  	if (ipv6_chk_addr(net, addr, NULL, 0))
  		return -EINVAL;
  
  	pac = sock_kmalloc(sk, sizeof(struct ipv6_ac_socklist), GFP_KERNEL);
  	if (pac == NULL)
  		return -ENOMEM;
  	pac->acl_next = NULL;
  	pac->acl_addr = *addr;
  
  	rcu_read_lock();
  	if (ifindex == 0) {
  		struct rt6_info *rt;
  
  		rt = rt6_lookup(net, addr, NULL, 0, 0);
  		if (rt) {
  			dev = rt->dst.dev;
  			dst_release(&rt->dst);
  		} else if (ishost) {
  			err = -EADDRNOTAVAIL;
  			goto error;
  		} else {
  			/* router, no matching interface: just pick one */
  			dev = dev_get_by_flags_rcu(net, IFF_UP,
  						   IFF_UP | IFF_LOOPBACK);
  		}
  	} else
  		dev = dev_get_by_index_rcu(net, ifindex);
  
  	if (dev == NULL) {
  		err = -ENODEV;
  		goto error;
  	}
  
  	idev = __in6_dev_get(dev);
  	if (!idev) {
  		if (ifindex)
  			err = -ENODEV;
  		else
  			err = -EADDRNOTAVAIL;
  		goto error;
  	}
  	/* reset ishost, now that we have a specific device */
  	ishost = !idev->cnf.forwarding;
  
  	pac->acl_ifindex = dev->ifindex;
  
  	/* XXX
  	 * For hosts, allow link-local or matching prefix anycasts.
  	 * This obviates the need for propagating anycast routes while
  	 * still allowing some non-router anycast participation.
  	 */
  	if (!ipv6_chk_prefix(addr, dev)) {
  		if (ishost)
  			err = -EADDRNOTAVAIL;
  		if (err)
  			goto error;
  	}
  
  	err = ipv6_dev_ac_inc(dev, addr);
  	if (!err) {
  		write_lock_bh(&ipv6_sk_ac_lock);
  		pac->acl_next = np->ipv6_ac_list;
  		np->ipv6_ac_list = pac;
  		write_unlock_bh(&ipv6_sk_ac_lock);
  		pac = NULL;
  	}
  
  error:
  	rcu_read_unlock();
  	if (pac)
  		sock_kfree_s(sk, pac, sizeof(*pac));
  	return err;
  }
  
  /*
   *	socket leave an anycast group
   */
  int ipv6_sock_ac_drop(struct sock *sk, int ifindex, const struct in6_addr *addr)
  {
  	struct ipv6_pinfo *np = inet6_sk(sk);
  	struct net_device *dev;
  	struct ipv6_ac_socklist *pac, *prev_pac;
  	struct net *net = sock_net(sk);
  
  	write_lock_bh(&ipv6_sk_ac_lock);
  	prev_pac = NULL;
  	for (pac = np->ipv6_ac_list; pac; pac = pac->acl_next) {
  		if ((ifindex == 0 || pac->acl_ifindex == ifindex) &&
  		     ipv6_addr_equal(&pac->acl_addr, addr))
  			break;
  		prev_pac = pac;
  	}
  	if (!pac) {
  		write_unlock_bh(&ipv6_sk_ac_lock);
  		return -ENOENT;
  	}
  	if (prev_pac)
  		prev_pac->acl_next = pac->acl_next;
  	else
  		np->ipv6_ac_list = pac->acl_next;
  
  	write_unlock_bh(&ipv6_sk_ac_lock);
  
  	rcu_read_lock();
  	dev = dev_get_by_index_rcu(net, pac->acl_ifindex);
  	if (dev)
  		ipv6_dev_ac_dec(dev, &pac->acl_addr);
  	rcu_read_unlock();
  
  	sock_kfree_s(sk, pac, sizeof(*pac));
  	return 0;
  }
  
  void ipv6_sock_ac_close(struct sock *sk)
  {
  	struct ipv6_pinfo *np = inet6_sk(sk);
  	struct net_device *dev = NULL;
  	struct ipv6_ac_socklist *pac;
  	struct net *net = sock_net(sk);
  	int	prev_index;
  
  	write_lock_bh(&ipv6_sk_ac_lock);
  	pac = np->ipv6_ac_list;
  	np->ipv6_ac_list = NULL;
  	write_unlock_bh(&ipv6_sk_ac_lock);
  
  	prev_index = 0;
  	rcu_read_lock();
  	while (pac) {
  		struct ipv6_ac_socklist *next = pac->acl_next;
  
  		if (pac->acl_ifindex != prev_index) {
  			dev = dev_get_by_index_rcu(net, pac->acl_ifindex);
  			prev_index = pac->acl_ifindex;
  		}
  		if (dev)
  			ipv6_dev_ac_dec(dev, &pac->acl_addr);
  		sock_kfree_s(sk, pac, sizeof(*pac));
  		pac = next;
  	}
  	rcu_read_unlock();
  }
  
  static void aca_put(struct ifacaddr6 *ac)
  {
  	if (atomic_dec_and_test(&ac->aca_refcnt)) {
  		in6_dev_put(ac->aca_idev);
  		dst_release(&ac->aca_rt->dst);
  		kfree(ac);
  	}
  }
  
  /*
   *	device anycast group inc (add if not found)
   */
  int ipv6_dev_ac_inc(struct net_device *dev, const struct in6_addr *addr)
  {
  	struct ifacaddr6 *aca;
  	struct inet6_dev *idev;
  	struct rt6_info *rt;
  	int err;
  
  	idev = in6_dev_get(dev);
  
  	if (idev == NULL)
  		return -EINVAL;
  
  	write_lock_bh(&idev->lock);
  	if (idev->dead) {
  		err = -ENODEV;
  		goto out;
  	}
  
  	for (aca = idev->ac_list; aca; aca = aca->aca_next) {
  		if (ipv6_addr_equal(&aca->aca_addr, addr)) {
  			aca->aca_users++;
  			err = 0;
  			goto out;
  		}
  	}
  
  	/*
  	 *	not found: create a new one.
  	 */
  
  	aca = kzalloc(sizeof(struct ifacaddr6), GFP_ATOMIC);
  
  	if (aca == NULL) {
  		err = -ENOMEM;
  		goto out;
  	}
  
  	rt = addrconf_dst_alloc(idev, addr, true);
  	if (IS_ERR(rt)) {
  		kfree(aca);
  		err = PTR_ERR(rt);
  		goto out;
  	}
  
  	aca->aca_addr = *addr;
  	aca->aca_idev = idev;
  	aca->aca_rt = rt;
  	aca->aca_users = 1;
  	/* aca_tstamp should be updated upon changes */
  	aca->aca_cstamp = aca->aca_tstamp = jiffies;
  	atomic_set(&aca->aca_refcnt, 2);
  	spin_lock_init(&aca->aca_lock);
  
  	aca->aca_next = idev->ac_list;
  	idev->ac_list = aca;
  	write_unlock_bh(&idev->lock);
  
  	ip6_ins_rt(rt);
  
  	addrconf_join_solict(dev, &aca->aca_addr);
  
  	aca_put(aca);
  	return 0;
  out:
  	write_unlock_bh(&idev->lock);
  	in6_dev_put(idev);
  	return err;
  }
  
  /*
   *	device anycast group decrement
   */
  int __ipv6_dev_ac_dec(struct inet6_dev *idev, const struct in6_addr *addr)
  {
  	struct ifacaddr6 *aca, *prev_aca;
  
  	write_lock_bh(&idev->lock);
  	prev_aca = NULL;
  	for (aca = idev->ac_list; aca; aca = aca->aca_next) {
  		if (ipv6_addr_equal(&aca->aca_addr, addr))
  			break;
  		prev_aca = aca;
  	}
  	if (!aca) {
  		write_unlock_bh(&idev->lock);
  		return -ENOENT;
  	}
  	if (--aca->aca_users > 0) {
  		write_unlock_bh(&idev->lock);
  		return 0;
  	}
  	if (prev_aca)
  		prev_aca->aca_next = aca->aca_next;
  	else
  		idev->ac_list = aca->aca_next;
  	write_unlock_bh(&idev->lock);
  	addrconf_leave_solict(idev, &aca->aca_addr);
  
  	dst_hold(&aca->aca_rt->dst);
  	ip6_del_rt(aca->aca_rt);
  
  	aca_put(aca);
  	return 0;
  }
  
  /* called with rcu_read_lock() */
  static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr)
  {
  	struct inet6_dev *idev = __in6_dev_get(dev);
  
  	if (idev == NULL)
  		return -ENODEV;
  	return __ipv6_dev_ac_dec(idev, addr);
  }
  
  /*
   *	check if the interface has this anycast address
   *	called with rcu_read_lock()
   */
  static bool ipv6_chk_acast_dev(struct net_device *dev, const struct in6_addr *addr)
  {
  	struct inet6_dev *idev;
  	struct ifacaddr6 *aca;
  
  	idev = __in6_dev_get(dev);
  	if (idev) {
  		read_lock_bh(&idev->lock);
  		for (aca = idev->ac_list; aca; aca = aca->aca_next)
  			if (ipv6_addr_equal(&aca->aca_addr, addr))
  				break;
  		read_unlock_bh(&idev->lock);
  		return aca != NULL;
  	}
  	return false;
  }
  
  /*
   *	check if given interface (or any, if dev==0) has this anycast address
   */
  bool ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
  			 const struct in6_addr *addr)
  {
  	bool found = false;
  
  	rcu_read_lock();
  	if (dev)
  		found = ipv6_chk_acast_dev(dev, addr);
  	else
  		for_each_netdev_rcu(net, dev)
  			if (ipv6_chk_acast_dev(dev, addr)) {
  				found = true;
  				break;
  			}
  	rcu_read_unlock();
  	return found;
  }
  
  
  #ifdef CONFIG_PROC_FS
  struct ac6_iter_state {
  	struct seq_net_private p;
  	struct net_device *dev;
  	struct inet6_dev *idev;
  };
  
  #define ac6_seq_private(seq)	((struct ac6_iter_state *)(seq)->private)
  
  static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
  {
  	struct ifacaddr6 *im = NULL;
  	struct ac6_iter_state *state = ac6_seq_private(seq);
  	struct net *net = seq_file_net(seq);
  
  	state->idev = NULL;
  	for_each_netdev_rcu(net, state->dev) {
  		struct inet6_dev *idev;
  		idev = __in6_dev_get(state->dev);
  		if (!idev)
  			continue;
  		read_lock_bh(&idev->lock);
  		im = idev->ac_list;
  		if (im) {
  			state->idev = idev;
  			break;
  		}
  		read_unlock_bh(&idev->lock);
  	}
  	return im;
  }
  
  static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
  {
  	struct ac6_iter_state *state = ac6_seq_private(seq);
  
  	im = im->aca_next;
  	while (!im) {
  		if (likely(state->idev != NULL))
  			read_unlock_bh(&state->idev->lock);
  
  		state->dev = next_net_device_rcu(state->dev);
  		if (!state->dev) {
  			state->idev = NULL;
  			break;
  		}
  		state->idev = __in6_dev_get(state->dev);
  		if (!state->idev)
  			continue;
  		read_lock_bh(&state->idev->lock);
  		im = state->idev->ac_list;
  	}
  	return im;
  }
  
  static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
  {
  	struct ifacaddr6 *im = ac6_get_first(seq);
  	if (im)
  		while (pos && (im = ac6_get_next(seq, im)) != NULL)
  			--pos;
  	return pos ? NULL : im;
  }
  
  static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
  	__acquires(RCU)
  {
  	rcu_read_lock();
  	return ac6_get_idx(seq, *pos);
  }
  
  static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
  {
  	struct ifacaddr6 *im = ac6_get_next(seq, v);
  
  	++*pos;
  	return im;
  }
  
  static void ac6_seq_stop(struct seq_file *seq, void *v)
  	__releases(RCU)
  {
  	struct ac6_iter_state *state = ac6_seq_private(seq);
  
  	if (likely(state->idev != NULL)) {
  		read_unlock_bh(&state->idev->lock);
  		state->idev = NULL;
  	}
  	rcu_read_unlock();
  }
  
  static int ac6_seq_show(struct seq_file *seq, void *v)
  {
  	struct ifacaddr6 *im = (struct ifacaddr6 *)v;
  	struct ac6_iter_state *state = ac6_seq_private(seq);
  
  	seq_printf(seq, "%-4d %-15s %pi6 %5d\n",
  		   state->dev->ifindex, state->dev->name,
  		   &im->aca_addr, im->aca_users);
  	return 0;
  }
  
  static const struct seq_operations ac6_seq_ops = {
  	.start	=	ac6_seq_start,
  	.next	=	ac6_seq_next,
  	.stop	=	ac6_seq_stop,
  	.show	=	ac6_seq_show,
  };
  
  static int ac6_seq_open(struct inode *inode, struct file *file)
  {
  	return seq_open_net(inode, file, &ac6_seq_ops,
  			    sizeof(struct ac6_iter_state));
  }
  
  static const struct file_operations ac6_seq_fops = {
  	.owner		=	THIS_MODULE,
  	.open		=	ac6_seq_open,
  	.read		=	seq_read,
  	.llseek		=	seq_lseek,
  	.release	=	seq_release_net,
  };
  
  int __net_init ac6_proc_init(struct net *net)
  {
  	if (!proc_net_fops_create(net, "anycast6", S_IRUGO, &ac6_seq_fops))
  		return -ENOMEM;
  
  	return 0;
  }
  
  void ac6_proc_exit(struct net *net)
  {
  	proc_net_remove(net, "anycast6");
  }
  #endif
  
  